TY - JOUR
T1 - Transcranial direct current stimulation over the primary motor cortex improves speech production in post-stroke dysarthric speakers
T2 - A randomized pilot study
AU - Wong, Min Ney
AU - Baig, Faisal Nouman
AU - Chan, Yeuk Ki
AU - Ng, Manwa L.
AU - Zhu, Frank F.
AU - Kwan, Joseph Shiu Kwong
N1 - Funding Information:
The study was unable to secure funding for its implementation and data collection. Later M. N. Wong received grant supports from the Research Grants Council Early Career Scheme (Grant Number 25609819) (https://www.ugc.edu. hk/eng/rgc/) and The Hong Kong Polytechnic University (Project Code: G-YBZN) (https://www. polyu.edu.hk/rio/) to support the data analysis and writing up of the study. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The authors would like to acknowledge the participants for their contribution to the project and thank the Hong Kong Stroke Association for their full support in participant recruitment.
Publisher Copyright:
© 2022 Wong et al.
PY - 2022/10/13
Y1 - 2022/10/13
N2 - Purpose The current study investigated the therapeutic potential of transcranial direct current stimulation (tDCS) on speech intelligibility, speech-related physiological and vocal functions among post-stroke dysarthric patients. Method Nine chronic post-stroke dysarthric patients were randomly assigned to the stimulation or sham group. The stimulation group received 2mA of anodal tDCS over the left inferior primary motor cortex for 15 minutes, while the sham group received 30s of stimulation under the same settings. All the participants received 10 daily 15 minutes of individualized speech therapy targeting their dominant phonological process or phonemes with the greatest difficulty. The outcome measures included (1) perceptual analysis of single words, passage reading and diadochokinetic rate, (2) acoustic analysis of a sustained vowel, and (3) kinematic analysis of rapid syllable repetitions and syllable production in sentence, conducted before and after the treatment. Results The results revealed that both the stimulation and sham groups had improved perceptual speech intelligibility at the word level, reduced short rushes of speech during passage reading, improved rate during alternating motion rate, AMR-kha1, and improved articulatory kinematics in AMR-tha1 and syllables /tha1/ and /kha1/ production in sentence. Compared to the sham group, the stimulation group showed significant improvement in articulatory kinematics in AMR-kha1 and syllable /kha1/ production in sentence. The findings also showed that anodal stimulation led to reduced shimmer value in sustained vowel /a/ phonation, positive changes in articulatory kinematics in AMR-tha1 and syllables /pha1/ and /kha1/ production in sentence at the post treatment measure. In addition to positive effects on articulatory control, reduced perturbation of voice amplitude documented in the stimulation group post treatment suggests possible tDCS effects on the vocal function. Conclusions The current study documented the beneficial effects of anodal tDCS over the primary motor cortex on speech production and suggested that combined tDCS and speech therapy may promote recovery from post-stroke dysarthria.
AB - Purpose The current study investigated the therapeutic potential of transcranial direct current stimulation (tDCS) on speech intelligibility, speech-related physiological and vocal functions among post-stroke dysarthric patients. Method Nine chronic post-stroke dysarthric patients were randomly assigned to the stimulation or sham group. The stimulation group received 2mA of anodal tDCS over the left inferior primary motor cortex for 15 minutes, while the sham group received 30s of stimulation under the same settings. All the participants received 10 daily 15 minutes of individualized speech therapy targeting their dominant phonological process or phonemes with the greatest difficulty. The outcome measures included (1) perceptual analysis of single words, passage reading and diadochokinetic rate, (2) acoustic analysis of a sustained vowel, and (3) kinematic analysis of rapid syllable repetitions and syllable production in sentence, conducted before and after the treatment. Results The results revealed that both the stimulation and sham groups had improved perceptual speech intelligibility at the word level, reduced short rushes of speech during passage reading, improved rate during alternating motion rate, AMR-kha1, and improved articulatory kinematics in AMR-tha1 and syllables /tha1/ and /kha1/ production in sentence. Compared to the sham group, the stimulation group showed significant improvement in articulatory kinematics in AMR-kha1 and syllable /kha1/ production in sentence. The findings also showed that anodal stimulation led to reduced shimmer value in sustained vowel /a/ phonation, positive changes in articulatory kinematics in AMR-tha1 and syllables /pha1/ and /kha1/ production in sentence at the post treatment measure. In addition to positive effects on articulatory control, reduced perturbation of voice amplitude documented in the stimulation group post treatment suggests possible tDCS effects on the vocal function. Conclusions The current study documented the beneficial effects of anodal tDCS over the primary motor cortex on speech production and suggested that combined tDCS and speech therapy may promote recovery from post-stroke dysarthria.
UR - http://www.scopus.com/inward/record.url?scp=85139880733&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0275779
DO - 10.1371/journal.pone.0275779
M3 - Journal article
C2 - 36227836
AN - SCOPUS:85139880733
SN - 1932-6203
VL - 17
JO - PLoS ONE
JF - PLoS ONE
IS - 10
M1 - e0275779
ER -